How to acquire a loan to start up a construction firm?

Stoo:
Any business loan at a bank will require that you show you've tapped your own money and that of the 3Fs (friends, family and fools.) If you can't convince those close to you to give you money (or random idiots who enjoy giving money away), no bank will take a risk on you. Those close to you have a far better idea what you're capable of, and if they won't help because they figure they'll lose their money, that's a big red flag.

If you can't tap any local funding, work in the industry – if you haven't worked in construction yet, don't start a firm, that's just a recipe for immediate failure. If you have, those you have worked with become sources of financing and partnership.

Steve D:
In the U.S., you will need a business plan (well written – that will take about 6 months of your time). While you are writing your business plan, start saving money – no lender will give you more than 80% (and most won't go over 70%) of your costs as outlined in your business plan. And do not be too optimistic in your projects for market or customers nor too pessimistic about your costs – the folks at the lender are experts in this and will know when your income projections are too high and your cost projections too low. You should also have 3 – 5 years of experience in the industry plus some management background.

tro:
you may not be able to
first of all most lenders require some kind of business plan one that covers what you might expect to do over the next five years
they also will want some history of what you have already done, on your own without outside help
if you have no experience in construction there is little chance you will get any kind of loan

Barkley:
Friends & family. Got strong collateral? Then Maybe a business loan if you meet other requirements.

michael:
Loans depend on collateral, capacity to repay, and the amount of equity available.